The development of the planetary exploration for landers makes it more and more necessary to have at our disposal small and light instruments. This is why we are developing in our laboratory a light imaging spectrometer with a wedge filter making the spectral splitting. This design already developed in other laboratories has the great advantage to need a limited number of optical components. However its drawback is that at a given instant the different spectral pixels don’t see the same spot in the field. We propose a new design to remedy this drawback by the adjunction of a dispersive system in the fore-optics.
The Small Explorer for Solar Eruptions (SMESE) mission is a French-Chinese satellite dedicated to the combined study of coronal mass ejections and flares. It should operate by the beginning of 2013. The spacecraft is based on a generic MYRIADE platform developed by CNES. Its payload consists of a Lyman α imager and a Lyman α chronograph (LYOT), a far infrared telescope (DESIR) and a hard X and γ ray spectrometer (HEBS). Its Sun-synchronous orbit will allow for continuous observations. <p> </p>LESIA (Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique, in Paris-Meudon Observatory) is in charge of DESIR instrument. DESIR (Detection of Eruptive Solar InfraRed emission) is an imaging photometer observing the sun in two bandwidths: [25; 45μm] and [80; 130μm]. <p> </p>The detector is a commercially available, uncooled microbolometer focal plane array (UL 02 05 1, from ULIS) designed for thermographic imaging in the 8-14 μm wavelength range. The 160x120 pixels are based on amorphous silicon, with dimensions 35x35 μm<sup>2</sup>. <p> </p>The performances in terms of noise and dynamics given by the manufacturer associated with simulations of a perfect quarter-wave cavity to predict the microbolometer absorption, make possible the use of such a detector to fulfil the DESIR detection specifications in the two FIR bandwidths. <p> </p>During the A Phase, tests have been carried out in our laboratory to validate the feasibility of the project. In this work, we present the first results obtained on the microbolometer performances in the FIR domain.
PLATO (PLAnetary Transits and Oscillation of stars) is a candidate for the M3 Medium-size mission of the ESA Cosmic Vision programme (2015-2025 period). It is aimed at Earth-size and Earth-mass planet detection in the habitable zone of bright stars and their characterisation using the transit method and the asterosismology of their host star. That means observing more than 100 000 stars brighter than magnitude 11, and more than 1 000 000 brighter than magnitude 13, with a long continuous observing time for 20 % of them (2 to 3 years). This yields a need for an unusually long term signal stability. For the brighter stars, the noise requirement is less than 34 ppm.hr<sup>-1/2</sup>, from a frequency of 40 mHz down to 20 μHz, including all sources of noise like for instance the motion of the star images on the detectors and frequency beatings. Those extremely tight requirements result in a payload consisting of 32 synchronised, high aperture, wide field of view cameras thermally regulated down to -80°C, whose data are combined to increase the signal to noise performances. They are split into 4 different subsets pointing at 4 directions to widen the total field of view; stars in the centre of that field of view are observed by all 32 cameras. 2 extra cameras are used with color filters and provide pointing measurement to the spacecraft Attitude and Orbit Control System (AOCS) loop. The satellite is orbiting the Sun at the L2 Lagrange point. This paper presents the optical, electronic and electrical, thermal and mechanical designs devised to achieve those requirements, and the results from breadboards developed for the optics, the focal plane, the power supply and video electronics.
LESIA (Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris-Meudon) has an extensive experience in visible and infrared imaging spectrometry with several instruments onboard planetary space missions (MarsExpress/OMEGA, VenusExpress/VIRTIS, Rosetta/VIRTIS).
On July 2020, NASA will launch the Mars2020 mission. This mission consists in landing an instrumented rover on the Martian surface in order to characterize the geology and history of a new landing site on Mars, investigate Mars habitability, seek potential biosignatures, cache samples for an eventual return to Earth, and demonstrate in-situ production of oxygen needed for human exploration.
NASA is developing the MARS 2020 mission, which includes a rover that will land and operate on the surface of Mars. MARS 2020, scheduled for launch in July, 2020, is designed to conduct an assessment of Mars’ past habitability, search for potential biosignatures, demonstrate progress toward the future return of samples to Earth, and contribute to NASA’s Human Exploration and Space Technology Programs.
The Exoplanet Characterisation Observatory, EChO, is a dedicated space mission to investigate the physics and chemistry of Exoplanet atmospheres. Using the differential spectroscopy by transit method, it provides simultaneously a complete spectrum in a wide wavelength range between 0.4μm and 16μm of the atmosphere of exoplanets. The payload is subdivided into 6 channels. The mid-infrared channel covers the spectral range between 5μm and 11μm. In order to optimize the instrument response and the science objectives, the bandpass is split in two using an internal dichroic. We present the opto-mechanical concept of the MWIR channel and the detector development that have driven the thermal and mechanical designs of the channel. The estimated end-to-end performance is also presented.
Nowadays, astronomers want to observe gaps in exozodiacal disks to confirm the presence of exoplanets, or even make actual images of these companions. Four hundred and fifty years ago, Jean-Dominique Cassini did a similar study on a closer object: Saturn. After joining the newly created Observatoire de Paris in 1671, he discovered 4 of Saturn’s satellites (Iapetus, Rhea, Tethys and Dione), and also the gap in its rings. He made these discoveries observing through the best optics at the time, made in Italy by famous opticians like Giuseppe Campani or Eustachio Divini. But was he really able to observe this black line in Saturn’s rings? That is what a team of optical scientists from Observatoire de Paris - LESIA with the help of Onera and Institut d’Optique tried to find out, analyzing the lenses used by Cassini, and still preserved in the collection of the observatory. The main difficulty was that even if the lenses have diameters between 84 and 239 mm, the focal lengths are between 6 and 50 m, more than the focal lengths of the primary mirrors of future ELTs. The analysis shows that the lenses have an exceptionally good quality, with a wavefront error of approximately 50 nm rms and 200 nm peak-to-valley, leading to Strehl ratios higher than 0.8. Taking into account the chromaticity of the glass, the wavefront quality and atmospheric turbulence, reconstructions of his observations tend to show that he was actually able to see the division named after him.
In this paper, we present the design of the MWIR channels of EChO. Two channels cover the 5-11 micron spectral
range. The choice of the boundaries of each channel is a trade-off driven by the science goals (spectral features of key
molecules) and several parameters such as the common optics design, the dichroic plates design, the optical materials
characteristics, the detector cut-off wavelength. We also will emphasize the role of the detectors choice that drives the
thermal and mechanical designs and the cooling strategy.
SAMI, the SCAO module for the E-ELT adaptive optics imaging camera MICADO, could be used in the first
years of operation of MICADO on the telescope, until MAORY is operational and coupled to MICADO. We
present the results of the study made in the framework of the MICADO phase A to design and estimate the
performance of this SCAO module.
MICADO is the adaptive optics imaging camera for the E-ELT. It has been designed and optimised to be mounted
to the LGS-MCAO system MAORY, and will provide diffraction limited imaging over a wide (~1 arcmin) field
of view. For initial operations, it can also be used with its own simpler AO module that provides on-axis
diffraction limited performance using natural guide stars. We discuss the instrument's key capabilities and
expected performance, and show how the science drivers have shaped its design. We outline the technical
concept, from the opto-mechanical design to operations and data processing. We describe the AO module,
summarise the instrument performance, and indicate some possible future developments.
The Corot project, developed in the framework of the CNES small satellite program with a wide European cooperation, will be launched in 2006. It is dedicated to seismology and detection of telluric planets. It will perform relative photometry in visible light, during very long (150 days) observing runs in the same direction. Both programs are running simultaneously and about 50.000 stars will be observed during the 3 years life. The concept of the instrument is based on an off-axis telescope (27 cm pupil, 3° square field of view), a dioptric objective images the stars on a focal plane. The focal plane is made of 4 CCDs, 2k*4k pixels, AIMO and frame transfer, at -40°C, two for each scientific programs. Electronics boxes manage the CCD readout, the thermal control and house-keeping, onboard software makes pre-processing and data reduction. As the expected signal is made of very small fluctuations expressed in ppm (part per million) a specific calibration of all the photometric chain and sub-systems is necessary. We have developed a specific test bench to calibrate CCDs. The manufacturer (E2V) provided us 10 CCDs and we realized calibration tests on them to be able to choose 4 CCDs for the flight focal plane (with different optimizations for the two scientific programs). Thereafter the camera sub-system has been integrated and calibrated on a specific test bench. This sub-system is made of a dioptric objective, focal plane, electronics boxes, mechanical and thermal equipment. We will present the camera sub-system (constraints and design), the test bench, and the results of the different tests : CCD calibration, radiation effects, Focal-Plane integration, optical setup, thermal balance and Camera calibration.